Acne-Prone Skin: Should I Choose a Dermatological Soap Bar?

In the research conducted by ARENS-CORELL M. & al. (1995), investigators assessed the effect of a acidic syndet bar (a type of dermatological soap bar formulated for skin susceptible to acne) versus standard soap on 120 adolescents and young adults with mild to moderate acne (I or II). Participants cleansed their faces twice daily over a span of 3 months. Starting with an average baseline of 13.4 inflammatory lesions, the syndet bar group saw a reduction to an average of 10.4 inflammatory lesions (which appears clinically significant and suggests a potential advantage), in contrast to the standard soap group, which saw an increase from 14.6 to 15.3. Symptoms of skin irritation were reported by 40.4% of standard soap users, whilst syndet bar users reported it in only 1.8%. This indicates superior efficacy and tolerance in the management of acne-prone skin with the acidic syndet bar.

In a separate study, VAROTHAI S. & al. (2015) assessed the pH levels of various types of cleansers designed for acne control that are available on the market, such as lotions, liquids, foams, and scrubs. Cleansers were dissolved to create 5% solutions, and the pH was immediately measured using a pH meter, with further verification provided by indicator strips. The results confirmed that all acne cleansing bars exhibited an alkaline pH (9.0 – 10.4), with the exception of syndet bars (neutral pH) and one bar for oily skin (acidic pH). The pH of the liquids for acne was found to range between 3.0 and 8.0, with the majority of liquid toners being more acidic than bars. Foams are either neutral or slightly alkaline, with only two brands recording normal skin pH (5.4 – 5.9). Approximately 60% of the acne scrubs had an acidic pH, whilst others displayed normal or alkaline pH.

Alkaline soap bars elevated skin pH by 1.5 – 2.0 units, disrupting the skin's natural acid mantle which typically has a pH of 4.5 - 5.5. This could lead to an increase in TEWL, resulting in dryness, irritation, and damage to the skin barrier. A high pH also fosters an environment conducive to the growth of acne-inducing bacteria (Cutibacterium acnes). All of these factors can instigate either exacerbated breakouts or inflammation in individuals with acne susceptible skin. In conclusion, alkaline soaps are not recommended for use on acne-prone skin. Conversely, acidic cleansers did not disrupt the skin microbiome to such a degree, reducing the likelihood of irritation, in addition to providing antibacterial protection. Liquid cleansers, particularly those containing amphoteric and nonionic surfactants, were generally well tolerated due to their lower pH.

From a pathological perspective, none of the findings from the current study definitively indicate the actual benefits to substantiate the presumption that acidic or pH-balanced cleansers would be more appropriate for acne-prone skin compared to abrasive scrubs and alkaline bars, which could, indeed, present drawbacks, particularly to skin that is already sensitive and susceptible to acne. Thus, if you are in search of a dermatological soap bar to treat acne-prone skin, ensure to select one labelled as an acidic syndet bar (and others that are specifically formulated for this skin type) and endeavour to avoid alkaline soap bars.